Wall clamp for electrical cords

ABSTRACT

A wall clamp assembly secured to a wall to retain a plug of an electrical appliance cord in a socket of a wall outlet. Cord is retained in a v-shaped opening of a clamping means at an outer end of a hinged arm of the assembly, the v-shaped opening having side walls with serrations or ridges. Load on the cord is sustained by the clamping means, the arm rotating to follow limited movement of the cord.

United States Patent 1191 McKeever 1 1 Jan. 2, 1973 [54] WALL CLAMP FORELECTRICAL [56] References Cited CORDS UNITED STATES PATENTS [76] Mcxem"443 East ll 2,913,791 11/1959 Martin .339/104 x Vanmuver, 15 Bmsh1,258,181 3/1918 Brown ..24/13o columblat Canada 3,538,484 11/1970Passofiume ..339/75 P x [22] Filed 1971 FOREIGN PATENTS 0R APPLICATIONS[21] APP! 208,721 564,766 11/1932 Germany ..339 105 Related UsApplication Data 323,268 l2/1929 Great Britain ..339/l05 [63]Continuation-impart of Ser. No. 26,280, April 7, PrimaryExaminer-Richard E. Moore 1970, abandoned. Attorney-Lyle G. Trorey [30]Foreign Application Priority Data [57} ABSTRACT April 1, 1970 Canada..078,789 A wall clamp assembly secured to a wall to retain a plug of anelectrical appliance cord in a socket of a [52] US. Cl. ..339/75 P,24/130 a tletcord is retained in a v-shaped opening of a [51] Int. Cl...H0lr 13/58 p g e s at a outer end of a hinged arm of the 58 Field ofSearch....339/l03, 95, 97, 75, 105, 104; assembly, the p Opening havingside walls with serrations or ridges. Load on the cord is sustained bythe clamping means, the arm rotating to follow limited movement of thecord.

10 Claims, 9 Drawing Figures 1 WALL CLAMP FOR ELECTRICAL CORDSCROSS-REFERENCES TO RELATED APPLICATIONS This is a continuation-in-partapplication of my copending application Ser. No. 26,280, filed Apr. 7,1970, and now abandoned.

BACKGROUND OF THE INVENTION 1. Field of the Invention The inventionrelates to a clamp that is used to retain electrical plugs in walloutlets.

2. Prior Art Commonly a plug at an end of a cord leading to an electricappliance has a tendency to being inadvertently pulled from the socketwhen the appliance is moved. Various devices have been invented directedto preventing this.

U.S. Pat. No. 2,659,059 issued to Johnson in 1953 is a retainer forelectrical plugs, the retainer being screwed to a standard outlet andhaving provision for accepting a limited range of plug sizes and shapes.This patent discloses a rigid retainer that requires unscrewing andscrewing of a screw to accommodate a plug in the retainer. U.S. Pat. No.3,102,922 issued to De Lashmutt in 1963 discloses a resilient retainerwhich is also screwed to a standard electrical outlet. The retainer inDe Lashmutt is adapted to accept cords of different diameters butproduces excessive cord bending when used with a thick cord, whichbending results in untimely damage.

Both of the above devices perform well and are adequate for a range ofplug sizes and cord thicknesses.

SUMMARY OF THE INVENTION The present invention relates to a wall clampadapted to retain a plug of a cord in a socket. The clamp is adapted tobe secured adjacent the socket and, with slack in a portion of the cordadjacent the plug, the cord is retained in a clamping means of the wallclampwhich means is free to follow limited lateral movements of anappliance connected to the cord when a portion of the cord between theclamp and the appliancetightens and the appliance is moved laterallyrelative to the socket. Because the cord is retained in the means of thewall clamp, load on the cord is carried mainly by the wall clamp so thatthe plug has little tendency to be pulled from the socket.

A detailed disclosure following, related to drawings, givesexemplification of preferred embodiment of the invention which'however,is capable of expression in structure other than that particularlydescribed and illustrated.

DESCRIPTION OF THE DRAWINGS FIG. 6 is a fragmented detail of a clampingmeans as seen from 6-6 FIG. 5, portions of cord shown in section,

FIG. 7 is a fragmented detail top plan of a further clamping means asshown in FIG. 5,

' FIG. 8 is a detail perspective of a portion of cord retaining means ofFIG. 7.

FIG. 9 is a fragmented detailed perspective of an alternative clampingmeans.

' In the detailed disclosure horizontal and vertical directions relateto the assembly as viewed in FIGS. 3 and 4.

DETAILED DISCLOSURE FIG. 1

A wall clamp assembly, generally 10, is shown in use vin a firstpositiombeing secured to a wall 12 adjacent a face plate of a commonelectrical outlet 11. Theoutlet ll-has a socket which accepts a plug 13at an end of an electrical cord 14 of a portable electrical device suchas an electrical power tool or toaster, hereinafter appliance. Theassembly is secured to the wall by screws 7 15. Means 20 of the assembly10 retains the cord so that the plug is not inadvertently pulled out ofthe socket. A cord portion 14.1 between the plug and the means 20 isslack, extending generally at right angles to the wall when viewed fromabove. A cord portion 14.2

extending from the means 20, hereinafter a clamping means, to theappliance may or may not be tight but, because the cord is held in theclamping means, load on the portion 14.2 is not transmitted to the plug13, and thus does not tend to pull the plug out of the socket. FIG. 2 r

In a second position, the clamp assembly 10 is shown adjacent a faceplate of an electrical outlet 18, the assembly being secured to a wall19. The outlet 18 has a socket which accepts a plug 21 at an end of acord 22, the cord being retained in the clamping means 20 as beforedescribed. A portion 22.1 of the cord between the plug and the clampingmeans is slack and a portion 22.2 from the clamping means to theappliance may be tight. The assembly is secured to the wall by screws23.

Tight herein refers to a condition of a cord that, without the clampingmeans 20, exerts aforce on the plug when the appliance is at a distancefrom the plug such that little or no slack is in the cord. The force mayarise because of stiffness-such that the cord remains bentunlessexcessive load is applied to straighten it; A flexible cord becomesstraightened under a smaller load than that required to straighten astiffer cord, however the stifier cord whilst bent may, if the applianceis moved, tend inadvertently to pull the plug from the socket. Thustightness in this context does not refer necessarily to straightness.FIGS. 1,3, 4, andS 1 The assembly 10 hasa body 27 having a rectangularpart 28 with a lower portion 29 and an upper portion 31. In FIGS. 1, 2,and 3, the body 27 is shown disposed vertically. An L-shaped extension30 has an arm extending outwards of the part 28, the arm having a lowerwall 30.1 and a downwardly inclinedv projection 32. The projection 32has an inner wall 32.1 spaced from thelower portion 29 defining in parta space accepting an arm 33. The clamping means 20 is provided at anouter end of the arm 33, the arm having an upper wall 33.1. The lowerportion 29 has a hole 34 which is aligned with a hole 35 in theprojection 32. The arm 33 has a hole 36 at an inner end 38, and when thearm 33 is between the projection 32 and the portion 29 the holes 34, 35,36, are aligned so that a shaft 37 passing through the holes journalsthe arm 33 for rotation about the shaft. Holes 16 and 17 are providedfor the screws and 23 respectively, for securing the body 27 to thewall. I

As seen in FIG. 3, the clamping means has two arms 41 and 42 withsloping inner side walls 44 and 45 converging to a curved apex 46, thesidewalls defining a v-shaped opening 43. As seen in FIG. 4, the arm 33is free to rotate about the shaft 37 in a direction shown by an arrow48, thus serving as a means for the arm, and with it the means 20, tofollow limited movement of the appliance when the cord is tight.Rotation in an upward direction is limited by interference of the upperwall 33.1 of the arm 33 with the lower wall 30.1 of the L- shapedextension 30 of the part 28. Thus mounting of the arm 33 on the shaft 37as above permits limited rotation of the arm about the shaft.

Depending on relative positions of the socket and of the appliance, theclamp assembly 10 can be mounted in an attitude which reduces forces onthe clamp by permitting rotation of the arm 33 to follow limitedmovements of the cord. These movements tend to be about extremepositions of the appliance and reduce load which, otherwise, would beapplied to the clamp. Movements of the appliance such that the arm 33rotates are, hereinafter and in the claims, referred to as limitedmovements of the appliance laterally about the socket.

For optimum arm rotation the clamp can be inverted, or mounted sideways,relative to attitudes of the clamp as shown in FIGS. 1 and 2. Thus meansare provided to secure the body 27 to the wall selectively with the armbelow the socket, above the socket or on either side of the socketaccording to direction at which-force tightening the cord is applied.Such rotation of the arm requires slack in the cord between the plug andthe clamping means 20, as shown in FIGS. 1 and 2, otherwise load on thecord can be transmitted to the plug, inadvertently pulling it from thesocket.

FIGS. 6, 7, and 8 As seen in FIG. 6, in the clamping means 20 the sidewalls 44and 45 of the v-shape'd opening 43 are inclined to each other'atan angle 49 and, in a first means to retain the cord, the side wallshave horizontally disposed serrations generally 50, the serrationshaving projecting spaced crests, spacing between the crests hereinafterbeing referred to as pitch. The crests are radiused'so as not to damagethe cord when it is inserted as later explained. Adjacent an upper edgeof the sidewall 45 the pitch of the crests is designated 51, andadjacent a lower edge of the side wall 45, the crests have a pitch 52,in FIG. 6 the pitch 52 is shown as being less than the pitch 51.Serrations on the side wall 44 of the vee are as described withreference to the serrations 50 and crests on the side. walls 44 aredisposed opposite to crests on the side walls 45, as shown. There isthus a gradual diminishing of the'pitch as the curved apex 46 isapproached. As the pitch diminishes, relative projection of the crestsfrom the side walls into the vee also diminishes, resulting in smallercrests. This structure provides means to accommodate cords of differentdiameters.

A cord of small diameter is designated 53 and shown in section adjacentthe apex 46. Opposite crests 54 of the serrations at the lower edge ofthe side walls 44 and deform the electrical cord and tend to retain itin the v-shaped opening. A cord of small diameter is thus retainedwithin the v-shaped opening 43 by the crests 54 of the serrations whichact as does a barb of a fish hook.

A cord 56 of large diameter, shown in section in broken outline, is heldbetween the side walls 44 and 45 in a position outward from the apexrelative to the cord 53 and issimilarly retained in the v-shapedopening. Horizontal movement of the cord through the opening is alsorestricted by the serrations. The v-shaped opening 43 can thusaccommodate a range of diameters of electrical cord. It is noted thatthe crests are shown as having sharp knife edges. Sharpness should besufficient merely to deform the cord as above, but not so sharp as todamage the cord, a small radius being -pro-' vided on the crests toreduce chance of damage. Cords having an outer casing with longitudinalflutes are gripped effectively by the serrations 50.

FIG. 7 shows an alternative means to retain a cord.

An alternative v-shaped opening 60 is shown in an al-.

temative clamping means 61 at anouter endof an alternative arm 62 shownfragmented. The v-shaped opening 60 has a plurality of tapering ridges63 on inwardly sloping side walls 64 and 65 of the v-shaped opening 60.A typical ridge '68 in the opening 60, shown in detail in FIG. 8, has anupper end 69, a lower end 70, and two sloping side walls 71 and, 72converging to a crest 73, the sidewall 71 not being seen clearly in FIG.8. At the end 69 of the ridge 68, the ridge projects a distance 74 fromthe sidewall 65. The lower end is flush with the side wall 65, thus thesloping side walls of the ridge are triangular. The distance 74 isdependent on flexibility and diameter of the cord and crests of theridge are radiused so that the cord is not damaged. An alternative ridge75 is shown in broken outline, and differs from theridge 68 byhaving aflattened crest 77, increasing surface area in contact with the cord.The alternative ridges 75 can be used in instances where sharp ridges,such as shown at 68, may damage the cord. v

In FIG. 7, the ridges 63 are regularly spaced on each side of and alongthe v-shaped opening 60, a ridge on one side being centered between tworidges on opposite sides, in other words theridges are staggered asshown. Whena portion of electrical cord is inserted'in the v-shapedopening, contact with the ridges alternates between one side of the cordand the other and, because of the staggered ridges 63, the cord followsan S-shaped path. With the cord embedded in the v-shaped opening, theridges increase resistance to being pulled horizontally, and offer someresistance to pulling of the cord upwards, thus serving as means toretain the cord within the v-shaped opening.

In the v-shaped openings 43 and 60 retention of the cord by the sidewalls of the opening is augmented by either the crests or the ridges,cord retention against pulling along one axis, usually being greaterthan when pulling occurs in a direction at right angles. The load on thecord between the clamp and appliance is not sustained by the plug, thuslittle force tending to pull the plug from the socket is transmitted bythe cord. FIG. 9

An alternative clamping means 80 is provided at an outer end 82 of anarm 81, equivalent to the arm 33 of FIG. 4. The means 80 has two spacedupwardly extending parallel walls 84 and 85, the wall 84 having twotapered buttresses 87 and 88 extending inwards from an inner surfacethereof, and the wall 85 having one tapered buttress 89 extendinginwards and being staggered between two buttresses 87 and 88. Thebuttress 88 has a sloping inner edge 91, which with an inner surface ofthe wall 85, defines a v-shaped gap, having a minimum and a maximumwidth. The minimum and maximum widths are sufficient to accommodate arange of diameters of electrical cord similar to the vshaped opening 43(FIG. 6). The buttresses 87 and 89 come within the description of thebuttress 88 and are not described.

When a cord (not shown) is inserted between the walls 84 and 85 itfollows a generally sinusoidal path between the buttresses and portionsof the opposing side walls. Thus the staggered buttresses and v-shapedgap between the buttresses and the side walls serve as a means to clampthe cord in an arm of the assembly.

I claim:

1. A wall clamp assembly (10) adapted to retain a plug (13,21) of anelectrical appliance cord (14,22) in a socket of a wall outlet (11,18),the assembly includa. means to secure the assembly to the wall,

b. a rigid arm (33) having an inner end (38) and an outer end, the innerend being connected to the securing means permitting the arm to swingabout the securing means,

c. means to clamp the cord at the outer end of the arm,

constructed and arranged so that a force tightening the cord is takenupin the arm, with a slack portion of the cord between the arm and theplug so that the force is not transmitted to the plug tending towithdraw it from the socket, the arm swinging to follow limited movementof the appliance when the cord is tight.

2. Structure as defined in claim 1 in which the means to clamp the cordin an arm of the assembly includes i. a v-shaped opening (43,60) havingsloping inner side walls (44,45; 64,65),

ii. means to retain the cord within the v-shaped opening provided on theside walls of the v-shaped opening.

3. Structure as defined in claim 2 in which the means to retain the cordwithin the v-shaped opening provided on the side walls of the v-shapedopening includes a plurality of horizontally disposed serrations (50)having crests (57,58) provided at a pitch on the sloping inner sidewalls (44,45), the crests on each side wall being opposite to eachother.

4. Structure as defined in claim 2 in which the means to retain the cordwithin the v-shaped opening provided on the side walls of the v-shapedopening includes a plurality of tapering ridges (63) each ridge havingan upper end (69) projecting a distance (74) from the side wall of the'v-shaped opening, a lower end (70) flush with the side wall of thev-shaped opening, the ridge havin two slo i side walls onver in to a orst (73), so that thg iifiges deform the cor ar id retain t e cord withinthe v-shaped opening.

5. Structure as defined in claim 2 in which the means to retain the cordwithin the v-shaped opening provided on the side walls of the v-shapedopening includes a plurality of tapering ridges (75), each ridge havinga flattened crest (77) and projecting a distance from side walls of thev-shaped opening so as to retain the cord within the v-shaped opening.

6. Structure as defined in claim 4 in which the ridges are staggeredalong sides of the v-shaped opening.

7. Structure as defined in claim 5, in which the ridges are staggeredalong sides of the v-shaped opening.

8. Structure as defined in claim 1 wherein the inner end of the arm ishinged on a shaft (37) so that the arm is free for limited rotationabout the shaft.

9. Structure as defined in claim 1 in which the means to secure theassembly to the wall includes means to secure the body to the wallselectively with the arm below the socket, above the socket, or oneither side of the socket according to direction at which the forcetightening the cord is applied.

10. Structure as defined in claim 1 in which the means (b) to clamp thecord in an arm of the assembly includes iii. two spaced extending walls(84,85) provided at an outer end of the arm,

iv. staggered tapered buttresses extending inwards from inner surfacesof the walls, the buttresses having sloping inner edges (91) definingv-shaped openings between the buttresses and portions of inner surfacesof the walls opposite, so that, when a cord is inserted between the sidewalls and the buttresses, the cord follows a generally sinusoidal pathand is gripped in the v-shaped openings.

1. A wall clamp assembly (10) adapted to retain a plug (13,21) of anelectrical appliance cord (14,22) in a socket of a wall outlet (11,18),the assembly including: a. means to secure the assembly to the wall, b.a rigid arm (33) having an inner end (38) and an outer end, the innerend being connected to the securing means permitting the arm to swingabout the securing means, c. means (20) to clamp the cord at the outerend of the arm, constructed and arranged so that a force tightening thecord is taken up in the arm, with a slack portion of the cord betweenthe arm and the plug so that the force is not transmitted to the plugtending to withdraw it from the socket, the arm swinging to followlimited movement of the appliance when the cord is tight.
 2. Structureas defined in claim 1 in which the means to clamp the cord in an arm ofthe assembly includes i. a v-shaped opening (43,60) having sloping innerside walls (44,45; 64,65), ii. means to retain the cord within thev-shaped opening provided on the side walls of the v-shaped opening. 3.Structure as defined in claim 2 in which the means to retain the cordwithin the v-shaped opening provided on the side walls of the v-shapedopening includes a plurality of horizontally disposed serrations (50)having crests (57,58) provided at a pitch on the sloping inner sidewalls (44,45), the crests on each side wall being opposite to eachother.
 4. Structure as defined in claim 2 in which the means to retainthe cord within the v-shaped opening provided on the side walls of thev-shaped opening includes a plurality of tapering ridges (63) each ridgehaving an upper end (69) projecting a distance (74) from the side wallof the v-shaped opening, a lower end (70) flush with the side wall ofthe v-shaped opening, the ridge having two sloping side walls convergingto a crest (73), so that the ridges deform the cord and retain the cordwithin the v-shaped opening.
 5. Structure as defined in claim 2 in whichthe means to retain the cord within the v-shaped opening provided on theside walls of the v-shaped opening includes a plurality of taperingridges (75), each ridge having a flattened crest (77) and projecting adistance from side walls of the v-shaped opening so as to retain thecord within the v-shaped opening.
 6. Structure as defined in claim 4 inwhich the ridges are staggered along sides of the v-shaped opening. 7.Structure as defined in claim 5, in which the ridges are staggered alongsides of the v-shaped opening.
 8. Structure as defined in claim 1wherein the inner end of the arm is hinged on a shaft (37) so that thearm is free for limited rotation about the shaft.
 9. Structure asdefined in claim 1 in which the means to secure the assembly to the wallincludes means to secure the body to the wall selectively with the armbelow the socket, above the socket, or on either side of the socketaccording to direction at which the force tightening the cord isapplied.
 10. Structure as defined in claim 1 in which the means (b) toclamp the cord in an arm of the assembly includes iii. two spacedextending walls (84,85) provided at an outer end of the arm, iv.staggered tapered buttresses extending inwards from inner surfaces ofthe walls, the buttresses having sloping inner edges (91) definingv-shaped openings between the buttresses and portions of inner surfacesof the walls opposite, so that, when a cord is inserted between the sidewalls and the buttresses, the cord follows a generally sinusoidal pathand is gripped in the v-shaped openings.